Bunched / Wrapped Cable
The question is tagged modeling and is pretty big, and I'm not going to make a full-blown tutorial (I wouldn't be able, and is off-topic), so I'm focusing on the basics, trying to get to a decent starting point and ignoring the modeling of details and the shading. 

The starting point is simply a curve. Start by adding a Bezier curve.

In Edit mode (Tab), select one of the two default handles and:


E extrude it to the opposite side, making sure to add some variation/randomness
repeat for several loops


rotate the handles in the view you've been using (select, R, repeat) to add randomness, or to align them (it really depends on how messy you want the cable)
change view and add some random displacement of the handles in the perpendicular direction (select, G, repeat)




You now want to add handles along the middle in order to control the shrinking. To do so:


select all your handles (A)
right click, Subdivide


Deselect all the vertices (AA) and select only the middle ones using a box select (B)
Shrink these handles along all axes except the long one, in my example: the X axis (S, shiftX)




The curve is done, now it requires some thickness.


Exit Edit mode (Tab), go to the Curve properties, and under Geometry, increase the Bevel > Depth.



You will probably see some overlaps, that can be fixed by moving some handles manually in edit mode.
The velcro strap can be done starting from a plane and extruding it around the middle: while doing it, look around often to check that it's not intersecting or staying too far from the wires. With a Subdivision Surface modifier, it will then look softer